1. Field of the Invention
The present invention relates to a sealed-type electric compressor having an electric motor and a compression mechanism within a compressor housing, suitable for use in a refrigerating cycle of an automotive air conditioning system.
2. Description of Related Art
Recently, a hybrid vehicle driven by a combustion engine and an electric motor, and an electric vehicle driven by an electric motor has been developed for reducing exhaust emissions. In accordance with the development of these vehicles, a sealed-type electric compressor driven by an electric motor has also been developed for an air conditioning system of these vehicles.
The electric compressor is installed in a vehicle engine compartment such that the rotor shaft thereof is horizontally arranged for lowering the height of hood to increase visibility.
In the electric compressor, refrigerant discharged from a compression mechanism flows through a motor chamber, where the electric motor is installed, to cool the motor, then is discharged from a compressor housing. However, when the refrigerant simply flows through the motor chamber, pressure-loss of the refrigerant increases. Thus, in general, a refrigerant passage is provided between the housing and a stator of the electric motor for guiding the refrigerant.
However, since the electric motor is installed such that the rotor shaft thereof is horizontally positioned, lubricating-oil lubricating sliding portions of the compressor is stored on the bottom of the motor chamber. The lubricating-oil stored in the motor chamber blocks the refrigerant passage formed at the lower portion of the compressor.
Thus, the cross-sectional area of the refrigerant passage is substantially reduced, so that the pressure loss of the refrigerant increases in the motor chamber. Further, the lubricating-oil stored on the motor chamber bottom is caught in the refrigerant, and is discharged with the refrigerant from the compressor.
In such a situation, when a predetermined amount of the lubricating-oil flows out of the compressor, the sliding portions are not sufficiently lubricated and the heat exchanging efficiencies of a condenser and a an evaporator are reduced.